The hip, knee, ankle and intervertebral discs of the spine are considered load-bearing joints, while the fingers and toes are considered non-weight bearing joints. The hip, knee, and ankle are further categorized as synovial joints, while the intervertebral discs are cartilaginous joints. These joints, especially the weight bearing joints, can undergo degenerative changes due to disease, age, trauma, repetitive loading and/or genetics.
For synovial joints, these degenerative changes come in the form of arthritis, or inflammation of the joint, leading to damage of the articular cartilage. Osteoarthritis mainly damages the joint cartilage, but there is often some inflammation as well. Rheumatoid arthritis is mainly inflammatory, and can eventually destroy the joint cartilage and adjacent bone. Fracture and other forms of trauma such as from sports injuries may also lead to degenerative changes.
Osteonecrosis is a condition in which either the bone of the femoral head or femoral condyles dies. The dead bone cannot withstand the stresses of walking and as a consequence, the femoral head or condyles then collapse, become irregular in shape, and cause pain in the hip or knee joints.
Osteoarthritis (OA) is the most common of the rheumatologic musculoskeletal disorders affecting about 21-26 million of the US adult population with the knee accounting for about 6.5 million of these cases.
Once the articular cartilage becomes deteriorated from OA, the result is bone rubbing against bone. The bone-on-bone friction causes discomfort ranging from feelings of stiffness to debilitating pain and eventual loss of motion.
Treatments for OA of the knee include conservative or non-pharmacological therapy, like physiotherapy, weight management and exercise; and more generally, intra-articular injections, arthroscopic surgery and knee replacement surgery. Whereas total or partial knee replacement surgery is considered an end-of-line intervention, the less invasive surgical procedures of lavage or debridement may be recommended for earlier and more severe disease.
Both arthroscopic lavage and debridement have been performed in patients with knee joint pain, with or without mechanical problems, refractory to medical therapy.
However arthroscopic lavage and debridement for osteoarthritis of the knee is still considered experimental and investigational by insurance companies because its effectiveness has not been established.
At this time, options that help to completely relieve severe osteoarthritis, include joint replacement or fusion. As examples, approximately 200,000 total knee joint and over 300,000 hip joint replacement operations are performed annually, and typically these artificial joints only last about 10-15 years.
Progression through the clinical pathway, however, is not linear, with treatment dependent on factors such as disease severity, patient preference, medical insurance reimbursement issues, and even the medical specialty of the physician the patient sees. In addition, some patients prefer not to have invasive surgery such as knee replacement; instead, they would prefer the less invasive injections and/or arthroscopic procedures.
It is therefore the object of the invention to provide a knee resurfacing implant, system, and method for treating patients experiencing moderate to severe OA knee pain who are either too young or too old to be candidates for total knee replacement surgery.
More particularly, the present invention relates to implantable systems, and corresponding insertion methods and procedures, which provide resurfacing of the knee joint anatomy on a minimally-invasive basis without bone resection and minimal native tissue disruption to reduce or eliminate joint pain and reestablish or maintain normal or near-normal joint stabilization and motion.